It will be appreciated that much of the population, both male and female, have taken up the laudable sport of running or jogging all in the name of acquiring aerobic exercise. Unfortunately, most runners do not have access to what is known as a cinder track which has the ability to soften or cushion considerably the impact of a runner. Hard surfaces as are normally found for use by runners are extremely injurious to the heels of runners unless proper precautions are taken to cushion the impact of the runner's foot on the running surface.
The need for a properly cushioned athletic shoe is even more important with regard to racing shoes which may be only two-thirds the weight of a long distance running shoe or a training shoe. (Long distance is usually defined as being greater than one mile). Consequently, with a racing shoe greater provision must be made to provide good cushioning propertie to the heel; i.e., especially to the calcaneus. It has been discovered that if the calcaneus is not properly cushioned, a jarring effect can be transferred through the ankle and up the leg to the spine, extending as far as the neck portion of the spine. Long periods of such mistreatment of the calcaneus might result in the formation of bone spurs thereon and other bones associated therewith.
Fortunately, the calcaneus ordinarily has a considerable layer of fat around the outwardly facing portion which provides some useful padding or cushioning. However, there is a tendency for some of the fat to be dissipated when it is abused by overuse. In such a situation, prior art concepts include an attempt to cup the fat and to urge it towards the center portion of the bottom of the calcaneus to emphasize its thickness where it is needed. In some instances this has been accomplished by using a plastic cup-like insert to, in effect, narrow the counter of the shoe to push the fat as heretofore noted. (The counter is, of course, a form-conferring stiffener for the heel portion of the shoe.)
In special circumstances it is often necessary to enlist the aid of a podiatrist who may prescribe an orthotic of post-formable material. Such a device may be constructed of a closed cell polyethylene foam having thermoforming or compression molding properties. The podiatrist conforms the top surface of the device to the foot by pressure and heat. The bottom of the device is laboriously formed to the shoe by employing a grinding wheel. Hard orthotics are also known which are designed for other purposes.
In any event a useful cushion pad device should also provide arch support extending from just in back of the first metatarsal joint to the back of the calcaneus. Normal arch support arrangements in shoes have been discovered to be of minimal value in this regard.